Method, communication arrangement, and communication device for transmitting message cells via a packet-oriented communication network

ABSTRACT

Message cells, cell comprising partially different priorities are transmitted via a first communication network. According to the invention, at least one of the message cells to be transmitted and comprising the same priority is added to a user data field of at least one data packet of a second packet-oriented communication network. A transmission priority (user priority) derived from the priority of the at least one added message cell, cell is associated with the data packet, according to which the at least one data packet is at least partially transmitted with the at least one added message cell, cell to/via the packet-oriented communication network. Advantageously, the message cells comprising the same priority or service category and pertaining to different virtual connections are added to a data or transmission frame of the packet-oriented communication network, thus fulfilling real time requirements.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International ApplicationNo. PCT/DE03/02354, filed Jul. 11, 2003 and claims the benefit thereof.The International Application claims the benefits of German applicationNo. 10233954.6 filed Jul. 25, 2002, both of the applications areincorporated by reference herein in their entirety.

FIELD OF INVENTION

This invention relates to a method, communication arrangement, andcommunication device for transmitting message cells via apacket-oriented communication network.

BACKGROUND OF INVENTION

The optimization of current communication networks, in particular ofbroadband user access networks—also known as access networks—aims toensure access to broadband services—e.g. Video-On-Demand—for a largenumber of users at a reasonable price. One optimization possibility isto distribute the devices and resources provided by the user accessnetworks (e.g. bandwidth and processing speed) over as many userconnections as possible. A further cost optimization possibility is toarrange the intelligent functions required for current message serviceslargely central in the user access network, so that, for example, theuser access assemblies or central assemblies arranged in thecommunication network, or in the respective network devices, onlyrequire to be equipped with as little functionality as possible.

Further, the technological and economic costs involved in realizingnetwork devices that can be arranged in current communication networkscan be reduced by using technologies not developed especially forbroadband user access networks but for the mass markets (e.g. personalcomputers). As an example of such a widespread and correspondinglydeveloped technology one might mention the Ethernet standardized inaccordance with Standard IEEE 802.3, which provides a frame or a packetoriented and connectionless transmission procedure. Ethernet basedtransmission systems are mainly used in local communication networks. Inthe case of network devices, such as for example multiplex devices (e.g.DSLAM, Digital Subscriber Line Access Multiplexer), that can be arrangedin current communication networks, it is for example known, to conveymessage cells organized according to the asynchronous transmissionmode-ATM—also referred to as ATM cells—via an Ethernet arranged locallyin the network device between user access assemblies arranged in thenetwork device and at least one central unit or assembly comprising thecentral functions of the network device. The Ethernet can be used bothas “wiring” or “backplane” in an assembly rack to bridge smallerdistances within the network device as well as an area-widecommunication network to bridge larger distances.

The aim of future communication networks is to transmit ever greaterdata volumes at high transmission rates from and to the end user,whereby this is to be achieved in particular by using Ethernet basedtransmission procedures. To achieve a transition from ATM based systemswhose realization involves great technical and hence financial costs toreasonably priced Ethernet based systems, it is especially necessary torun the ATM Service via system interfaces that are already based onEthernet transmission technologies in current communication networks.Thereby, in particular the ATM transmission technology “Quality OfService characteristics” must be maintained, whereby the availabletransmission capacity of current communication networks must be utilizedto a satisfactory degree.

In the publication “ATM Forum, Technical Committee, Frame-based ATMTransport over Ethernet (FATE), AF-FBATM-0139.00, February 2000” thereis, for example, the description of a method by which ATM cells aretransmitted via a communication network set up as an Ethernet. Adisadvantage of the method described is that it is limited to ATMconnections of the type AAL5. Thus this method can only be used to alimited extent in current and future user access networks, as in thesenetworks, when current data and communication services are realized, ATMcells of all AAL types are transmitted, especially the type AAL1 andAAL2. A further disadvantage of this method is that just the userinformation in the respective ATM cells to be transmitted via theEthernet—i.e. transport by AAL5 SSCS-PDUs—is added to the respectiveuser data field of the Ethernet frame, which makes it necessary for theATM cells that are to be transmitted to undergo a pre-processingprocedure involving a technological input. This approach to a solutioncannot be used in current user access networks as the AAL5 terminationoccurs with the user—i.e. at the CPE, Customer Premises Equipment—andthe transmission system for the transmission of AAL5 information shouldbe transparent. With the known method, a transparent transmission of theATM cells via the Ethernet is not possible.

In addition, with the known method an own Ethernet frame is used to thedisadvantage of each virtual connection—PVC, Permanent VirtualConnection—set up within the ATM communication network. Depending on thelength of the frame, there is a delay for individual ATM cells, asincoming cells must be held in intermediate storage until the Ethernetframe is full. This is especially unfavorable for real timeapplications. An obvious alternative of adding only one single ATM cellinto each Ethernet frame results, however, in the transmission resourcesprovided by the communication network being poorly utilized.

SUMMARY OF INVENTION

Thus the object of the invention is to improve the transmission of ATMcells via a packet or frame oriented communication network. Inparticular, a user access network should be created, in which ATM cellscomprising different AAL types and belonging in part to different ATMconnections are transmitted transparently while retaining the Quality OfService characteristics by means of the packet or frame orientedtransmission technology, and in particular by means of the Ethernettransmission technology. Based on a method according to the claims, theobject is achieved using the distinguishing features of said method.Further, based on a communication arrangement as well as on acommunication device in accordance with the claims, the object isachieved using the respective distinguishing features of saidarrangement and device.

With the method according to the invention, message cells to betransmitted in a first communication network are transmitted, at leastin part, via a second packet-oriented communication network. In thefirst communication network, several priorities are provided which canbe allocated respectively to the message cells to be transmitted,whereby the message cells are transmitted via the first communicationnetwork according to the priorities allocated in each case. Theessential aspect of the method according to the invention is that atleast one of the message cells to be transmitted and having the samepriority allocated is added to a user data field of at least one datapacket of the second packet-oriented communication network. Atransmission priority derived from the priority of the at least oneadded message cell is assigned to the at least one data packet, wherebythe at least one data packet together with the at least one addedmessage cell is at least partially transmitted to/via the secondpacket-oriented communication network according to the transmissionpriority assigned.

The main advantage of the method according to the invention lies in thatthe above mentioned disadvantages of the method arising from the FATEstandard are avoided. As opposed to the method described in thestandard, the information to be transmitted is transmitted transparentlyvia the packet-oriented communication network, thus the technical andfinancial costs for preprocessing the information to be transmitted canbe saved. In particular, the method according to the invention enablesoptimal utilization of the user access network-specific, star shapedconnection structure in which several users are connected via the useraccess network or access network to a network entry point of a highercommunication network. Advantageously, the message cells comprising thesame priority or service category and pertaining to different virtualconnections can be added to a data or transmission frame of thepacket-oriented communication network. In this way the individual datapackets and/or transmission frames are better filled within the presettime limits (Time Outs), hence complying with the preset prioritiesand/or real time requirements, thus achieving optimal utilization of thetransmission resources provided by user access networks. Further themethod according to the invention is not limited to a specificconnection type such as, for example, to type AAL5 ATM connections.

Advantageously, insert functions are provided in the first and/or secondcommunication network, by means of which functions for each priorityprovided in the first communication network respectively

the at least one data packet comprising the correspondingly derivedtransmission priority is formed,

the at least one message cell comprising the corresponding priority isadded to the user data field of the at least one data packet formed,

the at least one data packet is at least partially transmitted to/viathe second communication network.

By means of this advantageous development the data transmissionaccording to the invention can make use of a number, corresponding tothe number of the priorities provided in the first communicationnetwork, of transmission instances—for example, Ethernet instances—withdifferent prioritizing in order to realize the method according to theinvention.

Advantageously, the message cells to be transmitted via the firstcommunication network are transmitted within the framework of virtualconnections established across the first communication network, wherebythe respective allocated priority of the respective message cellstransmitted via one of the virtual connections represents aconnection-particular priority. Thanks to this advantageous design,message cells (for example, ATM cells), which are allocated to differentvirtual connections, i.e. which have different VPI/VCI values, but havethe same priority or are allocated the same service category, aretogether added to a data packet of the packet-oriented communicationnetwork. This achieves optimal utilization of the transmission resourcesprovided by the packet-oriented communication network.

According to a further advantageous embodiment of the method accordingto the invention, at least one further connection-particulartransmission parameter in addition to the connection-particular priorityis allocated to the message cells respectively transmitted via one ofthe virtual connections of the first communication network.

Advantageously, the insert functions are designed in such a way that theat least one message cell to be transmitted and comprising the sameassigned priority is added to the user data field of the respective atleast one data packet and the at least one data packet is at leastpartially forwarded to/via the packet-oriented communication networkaccording to the respectively assigned connection-particulartransmission parameter of the respectively at least one message celladded to the user data field. Using this advantageous embodiment ensuresin particular that Quality Of Service characteristics provided bycertain transmission procedures are retained. As part of thisdevelopment, the relevant data packets or frames formed are sent by theinsert instances each comprising different priorities if one of thefollowing conditions is fulfilled:

The payload quota of the respective data packet or frame formed isfilled, or

a preset dwell time of the at least one message cell added to the userdata field of the data packet is exceeded when filling the user datafield.

Thus regardless of the respective data traffic volume, preset delays arenot exceeded.

According to a further development of the method according to theinvention, the first communication network is designed in accordancewith the asynchronous transfer mode-ATM, and the packet-orientedcommunication network and the data packets transmitted in said networkdesigned according to the IEEE Standard 802.3.

Advantageously, the insert functions are designed in such a way that theat least one message cell to be transmitted and comprising the sameallocated priority is added to the user data field of the respective atleast one data packet and the at least one data packet is at leastpartially forwarded to/via the packet-oriented communication networkaccording to the smallest preset “Cell Delay Variation Tolerance” valueof the respective at least one message cell added to the user datafield. By means of this advantageous development of the method accordingto the invention, the time for filling a data packet is monitored, thusensuring that the message cells to be transmitted are not unacceptablydelayed and that the current data packet formed is sent or forwarded onschedule.

Advantageously, the data packets transmitted via the secondpacket-oriented communication network are in addition designed accordingto the Standard IEEE 802.1Q-1998, whereby the transmission priorityrespectively allocated to a data packet transmitted via the secondcommunication network is determined by the “user_priority” informationin the “Tag Control Information” data field (TCI) of the “Ethernetencoded tag header”. By means of this advantageous development and usingthe IEEE Standard 802.1Q-1988, it is made especially easy to assign ATMService Classes directly to “Ethernet User Priorities”.

Further advantageous embodiments of the method according to theinvention and a communication arrangement and a communication device areto be found in the further claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the method according to the invention is explained ingreater detail with the help of several drawings.

These show:

FIG. 1 an application scenario arranged in a user access network, inwhich scenario the method according to the invention is brought intoaction,

FIG. 2 a connection unit arranged in a multiplexer device (DSLAM) forrealizing the method according to the invention,

FIG. 3 the structure of a control unit arranged in a connection unit orin a central unit for executing the method according to the invention,

FIG. 4 in a functional logic diagram, the ATM specific processing of theinformation or ATM cells to be transmitted under the method according tothe invention,

FIG. 5 in a functional logic diagram, the Ethernet specific processingof the information or ATM cells to be transmitted under the methodaccording to the invention,

FIG. 6 an Ethernet frame formed in accordance with the method accordingto the invention and within the scope of the IEEE Standard 802.1Q-1988and having ATM cells added to the user data field and an assigned or“mapped” ATM Service Class or transmission priority.

DETAILED DESCRIPTION OF INVENTION

In a logic diagram, FIG. 1 shows a communication device or multiplexdevice DSLAM arranged in a user access network or access network ACCESSdesigned according to the asynchronous transfer mode-ATM—, to whichcommunication device the respective users—or CPE, not illustrated—areconnected via several connection units AE1 . . . Z and via several useraccess lines TLN1 . . . n or TLN1 . . . k. In this embodiment, therespective users are connected, for example, via an xDSL transmissionprocedure to connections PORT correspondingly provided for this purpose,of the respective connection units AE1 . . . z. A packet-orientedcommunication network EN—also called “Ethernet” in thefollowing—designed in accordance with the IEEE Standard 802.3, isarranged in the communication device DSLAM, and to which communicationnetwork are attached the respective connection units AE1 . . . z.Another central unit ZE arranged in the center of the communicationdevice DSLAM is connected to the Ethernet EN. An Ethernet MAC addressmacl . . . x . . . z (MAC, Medium Access Control) is assigned to theconnection units AE1 . . . z as well as to the central unit ZErespectively, which address uniquely identifies them within the EthernetEN.

The central unit ZE is connected to a first input ED1 of thecommunication device DSLAM via a first input EZ1. Connected to thisfirst input ED1 there is a first higher communication network KN1, alsodesigned, for instance, in accordance with the IEEE Standard 802.3. Thefirst higher communication network KN1 can also, for instance, bedesigned as a Gigabit Ethernet, which is, for example, connected to thefirst input ED1 of the communication device DSLAM via a 1000 BASE LXconnection.

The central unit ZE arranged in the communication device DSLAM has asecond input EZ2, which is connected to a second input ED 2 provided inthe communication device DSLAM. In accordance with the applicationscenario, a further higher communication network KN2, designed inaccordance with the asynchronous transfer mode ATM, is connected to thissecond input ED 2.

The users connected to the communication device DSLAM are connected tothe two higher communication networks KN1, KN2 via the respectiveconnection units AE1 . . . z, via the Ethernet EN and via the centralunit ZE. Control tools CONT for carrying out the method according to theinvention are provided in the respective connection units AE1 . . . z aswell as in the central unit ZE. Further network processing tools NVM,for example, to carry out traffic management and process headerinformation (header translation) are allocated to the control tools CONTarranged in the respective units AE1 . . . z, ZE. At least the networkprocessing tools NVM provided on the central unit ZE can includeadditional tools to carry out segmentation and reassembly (e.g. AAL5SAR).

In FIG. 2 the structure of a connection unit AE 1 . . . z arranged inthe communication device DSLAM on the user side is illustrated. Arrangedin the connection unit AE1 . . . z are several xDSL modems xDSL-MOD, toeach of which a user access line TLN designed in accordance with thexDSL transmission procedure is connected via an appropriately designedconnection PORT. The individual xDSL modems are connected to the controlunit CONT via a Utopia interface UTOPIA in accordance with the ATMtransmission procedure. The control unit CONT is connected to theEthernet EN—not illustrated in FIG. 2—via an internal interface, forexample an xMII interface, Medium Independent Interface—and via aconnection A. The central unit ZE, which is not described in detail, isdesigned correspondingly.

In FIG. 3 the functional structure of the control unit CONT arranged ineach connection unit AE1 . . . z or central unit ZE is described in moredetail. The control unit CONT—also called a converter—is made up of anATM specific processing stage ATM_PROC and an Ethernet specificprocessing stage EN_PROC, which are connected with each otherinternally. The ATM processing stage ATM_PROC is connected to the Utopiainterface UTOPIA. The Ethernet processing stage EN_PROC is connected tothe Ethernet via the internal xMII interface. Both processing stagesATM_PROC, EN_PROC can be connected via a microcontroller interface MPSto a microcontroller—not illustrated—to carry out maintenance andadministrative tasks.

The following functions are supported by the ATM processing stageATM_PROC:

Utopia L2 Interface

Header translation

Memory tools to process header field information (header translationtable)

Traffic management to control queues and to control the respectiveoutputs (queue and port scheduling)

Queue routines for the intermediate storage of ATM cells.

It is assumed for the embodiment illustrated in FIG. 1 that, startingfrom a communication device—not illustrated—connected to the firstconnection unit AE1 via the first user access line TLN1, information orATM cells are transmitted via a virtual connection—represented in FIG. 1by a broken line double arrow vc1—via the Ethernet EN and the centralunit ZE to a destination—not illustrated—arranged in the firstcommunication network KN1. It is further assumed that, starting from acommunication device connected to the first connection unit AE1 via then^(th) user access line TLMn, information or ATM cells are transmittedvia a second virtual connection—represented in FIG. 1 by a broken linedouble arrow vc2—via the Ethernet EN and the central unit ZE to adestination—not illustrated—arranged in the higher second communicationnetwork KN2. It is further assumed that the ATM cells cell(vc1),cell(vc2) transmitted via the two virtual connections vc1,2 are eachassigned to the ATM Service Class CBR.

In the following the method according to the invention is explained inmore detail:

As opposed to the Frame-Based-ATM-Over-Ethernet Standard (FATE) of theATM Forum mentioned above, according to the invention at least onecomplete ATM cell, i.e. at least one comprising a destination and userdata field, is transmitted with 53 bytes data volume, which can beassigned to different virtual connections—here vc1 and vc2. Further themethod according to the invention is not limited to the connection typeAAL 5. According to the invention ATM cells arriving at thecommunication device DSLAM, or at the connection units AE1 . . . z, orat the central unit ZE, and to be forwarded accordingly, are added tothe user data field nf or payload field of an Ethernet frame dp of theEthernet EN arranged within the communication device DSLAM byaccordingly provided control or insertion tools CONT. An Ethernet framedp can contain 1 to n message or ATM cells, whereby the number n of theadded ATM cells is only limited by the maximum possible length of anEthernet frame according to the standard. According to the standard, thenormal length of an Ethernet frame is set at 1536 bytes. In certainapplications, this length can, however, be increased.

As can be seen from FIG. 2 and FIG. 3, the ATM cells cell(vc1),cell(vc2) transmitted from the users via the respective user accesslines TLN1,n and via the respective xDSL modem, xDSL-MOD, to the firstconnection unit AE1, are transmitted via the Utopia interface UTOPIA tothe control unit CONT arranged in the connection unit AE1. According toFIG. 3 the ATM cells cell(vc1), cell(vc2) arriving at the control unitCONT are forwarded first to the ATM processing unit ATM_PROC.

The functional structure of this ATM processing unit ATM_PROC isdescribed in more detail in FIG. 4. The ATM cells cell(vc1), cell(vc2received by the Utopia interface are first translated by the headerfield processing unit Header-Trans according to the “Header TranslationTable” information stored in the memory MEM, i.e. the VPI/VCI values(Virtual Path Identifier, Virtual Channel Identifier) held in the headerfield of the respective ATM cells are modified correspondingly. This isnecessary as in user access networks implementation requires that therespective ATM cells are usually sent with the same VPI/VCI values fromthe user side and thus normally there is no possibility ofdistinguishing between the individual established virtual connections orPVCs (Permanent Virtual Connections). After the translation, theindividual ATM cells cell(vc1), cell(vc2) are forwarded by celldistribution tools Cell-Dist according to their associated ATM serviceclass in the familiar way to the accordingly arranged queues. Thefollowing ATM service classes, for example, are supported by the ATMprocessing unit ATM_PROC:

CBR (Constant Bit Rate)

rt-VBR (real time Variable Bit Rate)

nrt-VBR (non real time Variable Bit Rate)

UBR (Unspecified Bit Rate)

UBR+

As can be seen from FIG. 4, an appropriate queue WS is provided for eachof the supported ATM service classes, in which queue the respective ATMcells arriving are distributed and stored by the cell distribution toolsCell-Dist. The individual queues WS are each assigned queue read toolsWFQ, schedulers, by means of which the ATM cells arranged in theindividual queues WS are read according to their respective priority orATM service class and are forwarded to the Ethernet processing unitEN_PROC. The read tools WFQ, schedulers, support “Strict PriorityScheduling”, so that the ATM cells with the highest priority are readand sent first. It should be noted that the ATM cells arriving at theATM processing unit ATM_PROC and the ATM cells to be forwarded in thedirection of the user are distributed and read in the appropriate mannerin respective queues provided for this and forwarded via the Utopiainterface UTOPIA—illustrated in the bottom half of FIG. 4.

The functional structure of the Ethernet processing unit EN_RPOC isillustrated in FIG. 5. For each ATM service class provided in the ATMuser access network ACCESS tools are provided to form Ethernet dataframes—in the following called “Frame Assembly Instances” CBR_FA,rt_VBR_FA, nrt_VBR_FA, UBR/UBR+_FA—by means of which the respective ATMcells cell(vc1), cell(vc2) are added or mapped to the respectiveEthernet frame formed. Several ATM cells with different VPI/VCI valuescan be mapped to an Ethernet frame at a time. According to theinvention, however, it is always only ATM cells of one service classthat are added to the same Ethernet frame dp. In the applicationscenario illustrated in FIG. 1, the ATM cells cell(vc1), cell(vc2)transmitted via the two virtual connections vc1, 2 set up andrespectively comprising the ATM service class “Constant Bit Rate, CBR”are forwarded by the cell distribution tools Cell-Dist to the FrameAssembly Instance CBR_FA provided correspondingly for this. According tothe sequence transmitted from the ATM processing unit ATM_PROC, the ATMcells of both virtual connections cell(vc1), cell(vc2) are added to anEthernet data frame dp by the Frame Assembly Instance CBR_FA—see FIG. 6.

As can be seen from FIG. 6, the Ethernet data frame dp is designed inaccordance with the IEEE Standard 802.1Q-1998. This Ethernet data framedp contains a modified header field kf—called “VLAN-Tag” in FIG. 6—witha specific “user_priority” in the “Tag Control Information Field” (TCI).According to the invention, a transmission priority corresponding to thepriority of the ATM cells added respectively to the user data field nfof the respective Ethernet data frame dp is entered into the“user_priority” field of the TCI field. The application of the “TagFrame Format” and the structure of the TCI field of the “Ethernetencoded tag header” ETPID is described under Point 9.3 of the IEEEStandard 802.1 Q-1998.

The mapping as described and using the IEEE standard 802.1Q-1998 ensuresthat each ATM service class can be mapped to a corresponding “EthernetUser_Priority”. A separate VLAN identifier or VLAN user priority can beallocated for each ATM service class. Below a proposal for a possiblemapping of ATM service classes to “VLAN User Priority” is set out in theform of a table. ATM Service Class VLAN User Priority CBR 6 RealTime-VBR 5 Non Real Time VBR 4 UBR 0 (default)

This proposal ensures that ATM cells with the highest priority are alsotransmitted or dealt with in the Ethernet EN with sufficiently highpriority. Thus, by applying the “Class Of Service” characteristics, ATMcells can also be transmitted by means of Ethernet switches viacommunication networks locally extended and designed in accordance withthe Ethernet transmission procedure.

The length of the Ethernet data frames dp constructed by the respectiveFrame Assembling Instances CBR_FA, rt_VBR_FA, nrt_VBR_FA and UBR/UBR+_FAresults from the type of the data traffic to be transmitted at the time,i.e. from the respective priority or ATM service class of the ATM cellsadded at the time. If, for example, an Ethernet data frame dp is formedwith ATM cells added to it, which cells run real time data traffic (i.e.rt-VBR), then this Ethernet data frame must be restricted in size.Otherwise the dwell time of the first ATM cell added to the Ethernetdata frame dp would become too long, thus resulting in increased delaytimes or delays and the real time requirements can no longer befulfilled.

Fulfilling real time requirements represents, however, an essential partin the transmission of ATM cells via a communication network EN designedin accordance with the Ethernet transmission procedure. A delay timedependent frame assembling was realized according to the invention inorder to fulfill this requirement. This said frame ensures thatspecified dwell times of the ATM cells added to the respective Ethernetdata frames dp are not exceeded. It is known from the ATM transmissiontechnology that when a virtual ATM connection is created, the instancesinvolved agree or negotiate further connection-particular transmissionparameters in addition to the respective ATM service class. Forinstance, the ATM conforming “Cell Delay Variation Tolerance” or CDVT isan example of such a transmission parameter. According to the invention,the length of the Ethernet data frames dp formed by the respective FrameAssembling Instances CBR_FA, rt_VBR_FA, nrt_VBR_FA and UBR/UBR+_FA isassigned both by the respective ATM service class and by the respectiveconnection-particular transmission parameters—here, for instance, by theconnection-particular assigned Cell Delay Variation Tolerance, CDVT. Thelower the CDVT value assigned for an ATM connection is, the greater isthe real time requirement and the shorter the respective Ethernet dataframe dp formed must be. If ATM cells of different virtualconnections—e.g. cell(vc1), cell(vc2)—are added to an Ethernet dataframe dp, then the length of the Ethernet data frame dp is determined bythe smallest CDVT value present in the respective ATM cells to be addedto this data frame.

As can be seen from FIG. 5, each Frame Assembling Instance CBR_FA,rt_VBR_FA, nrt_VBR_FA and UBR/UBR+_FA is allocated a configurable timerT1 . . . 4, which controls the formation of the respective Ethernet dataframes dp. Each timer T1 . . . 4 is initiated when the first ATM cell isread in or added to the respective Ethernet data frame dp. The timer T1. . . 4 is used to monitor the time for filling an Ethernet data framedp and also to monitor that the Ethernet data frames formed are sent ontime. Thereby the times t1 . . . 4 assigned by the individual timers T1. . . 4 are dependent on the respective lowest CDVT value of therespective ATM cells to be added to an Ethernet data frame dp. If, forexample, ATM cells of the ATM service class CBR with a very low CDVTvalue are transmitted (these ATM cells belong, for example, to apermanently established virtual connection with high real timerequirements), then this timer—here e.g. T1—has a very low value t1,i.e. the respective ATM cells to be added only dwell in the FrameAssembling Instance CBR_FA for a very short period of time, so that onlyrelatively short Ethernet data frames DP are formed by this instance. Inthe worst-case scenario, only one ATM cell at a time is transmitted perEthernet data frame. It should be noted that the maximum dwell time ofATM cells in the respective Frame Assembling Instance CBR_FA, rt_VBR_FA,nrt_VBR_FA and UBR/UBR+_FA can be set separately for each ATM serviceclass. For example, according to the embodiment, the following relationscan apply between the timers: t1<t2<t3<t4. In FIG. 5 the length of therespective Ethernet data frames dp formed resulting from this relationis illustrated respectively by a broken line rectangle.

The times t1 . . . 4 assigned by the individual timers T1 . . . 4 can beconfigured by external network management—e.g. when setting up theindividual ATM connections—as well as at the run time, so that ATMconnections temporarily set up—“switched circuit connections”—are takeninto account.

The Ethernet data frames dp formed by the individual Frame AssemblingInstances CBR_FA, rt_VBR_FA, nrt_VBR_FA and UBR/UBR+_FA and designed inaccordance with the IEEE standard 802.3 or 802.1Q-1998 are forwarded toan access unit MAC for controlling the access to the transmissionmedium—here the Ethernet conforming communication network EN. Via theaccess unit MAC, the Ethernet data frames dp to be transmitted areforwarded to the Ethernet EN via an internal interface xMII. TheEthernet data frames dp transmitted to the Ethernet EN are transmittedvia the latter to a destination—in this embodiment the central unitZE—assigned by the destination information contained in the header fieldkf of the respective Ethernet data frame. The ATM cells cell(vc1),cell(vc2) transmitted in this way to the destination, i.e. to thecentral unit ZE, are extracted from the respective Ethernet data frameby the control tools CONT, whereby the information to be transmitted viathe first virtual connection vc1—i.e. the payload quota of the ATM cellscell(vc1)—is converted in known manner by the control unit CONT arrangedin the central unit ZE into information that conforms to the IEEEstandard 802.3, i.e. Ethernet data frames, and is forwarded to the firstcommunication network KN1. The information or ATM cells cell(vc2) to betransmitted via the second virtual connection vc2 are forwarded by thecontrol unit CONT to the second communication network KN2 designed inaccordance with the ATM.

The method according to the invention has the advantage that ATM cellscomprising different VPI/VCI values but assigned to the same ATM serviceclass can be added to an Ethernet data frame together and transmittedvia the Ethernet transparently. This allows the Ethernet overhead to bereduced, whereby, at the same time, a limit is set on the time requiredfor the mapping of the ATM cells in the Ethernet data frame (FrameAssembling Time). The number of ATM cells to be added at a time to anEthernet data frame dp—i.e. the fill status of the respective payload ofan Ethernet data frame—is controlled in the way according to theinvention per frame assembling instance firstly by the respective ATMservice class and also by an additional connection-particulartransmission parameter—e.g. CDVT value—of the respective ATM cells to beadded. Hereby, per frame assembling instance, the respective lowest CDTVvalue of the respective ATM cells to be added is taken intoconsideration, so that the delay of the ATM cells when they are beingadded to the respective Ethernet data frame is monitored and unnecessarydelays are prevented.

It should be noted that when the Ethernet data frames are being filledwith ATM cells further connection-particular transmission parameters canbe taken into consideration. By this means, the dwell time arising whenan ATM cell is transmitted is limited to a previously defined value evenwhen the traffic occurrence is low, so that the method according to theinvention can be set even more precisely to real time requirements thathave to be met.

Further it should be noted that the cell oriented user access networkACCESS illustrated in FIG. 1 can be designed in accordance with anotherpacket-oriented transmission procedure—e.g. in accordance with theInternet protocol or TCP/IP—so that, using the method according to theinvention, instead of the message cells any type of data packetswhatsoever—possibly with prior segmentation or reassembling, “SAR”—canalso be added to the data packets or Ethernet data frames of the secondcommunication network.

1.-20. (canceled)
 21. A method for at least partially transmitting amessage cell in an access communication network via a packet-orientedcommunication network, the access communication network havingpriorities that can be assigned to the message, the message cell istransmitted via the access communication network in accordance with thepriorities assigned comprising: adding the message cell to a user datafield of a data packet of the packet-oriented communication network,each message cell added to the same user data field having the sameassigned priority; deriving a transmission priority from the priority ofthe added message cell; assigning the derived priority to the datapacket; and partially transmitting the data packet according to theassigned transmission priority via the packet-oriented communicationnetwork.
 22. The method according to claim 21, wherein insert functionsare provided in the communication network selected from the groupconsisting of access communication network, packet-orientedcommunication network, and combination thereof by means of whichfunctions, for each priority provided in the first communication networkrespectively the data packet comprising the correspondingly derivedtransmission priority is formed, the message cell comprising thecorresponding priority is added to the user data field of the datapacket, and the data packet is at least partially transmitted via thepacket-oriented communication network.
 23. The method according to claim21, wherein the message cell is transmitted within the framework of thevirtual connections set up over the access communication network, theassigned priority of the message cell transmitted via one of the virtualconnections represents a connection-particular priority.
 24. The methodaccording to claim 23, wherein a further connection-particulartransmission parameter in addition to the connection-particular priorityis assigned to the message cell.
 25. The method according to claim 24,wherein the insert functions are designed such that the message cell isat least partially forwarded via the packet-oriented communicationnetwork according to the further connection-particular transmissionparameter of the message cell.
 26. The method according to claim 21,wherein the access communication network is designed in accordance withthe asynchronous transfer mode, in that by means of the prioritiesprovided in the access communication network respectively, a traffictype defined in accordance with the asynchronous transfer mode forum andITU-T is represented, or a specific asynchronous transfer mode serviceclass is represented.
 27. The method according to claim 26, wherein acell delay variation tolerance specified as part of an establishedasynchronous transfer mode connection is represented by the furtherassigned connection-particular transmission parameter.
 28. The methodaccording to claim 27, wherein the insert functions are designed in sucha way that the message cell is partially forwarded via thepacket-oriented communication network according to the lowest specifiedcell delay variation tolerance value of the message cell.
 29. The methodaccording to claim 21, wherein the second packet-oriented communicationnetwork and the data packets transmitted therein are designed inaccordance with the IEEE standard 802.3.
 30. The method according toclaim 29, wherein the data packets transmitted via the packet-orientedcommunication network are designed in accordance with the IEEE standard802.1 Q-1998, whereby the transmission priority allocated to the datapacket transmitted is determined by the user_priority information in thetag control information data field of the Ethernet-encoded tag header.31. The method according to claim 21, wherein information representing anumber of the message cells added to the user data field is added to thedata packet.
 32. The method according to claim 21, wherein a destinationinformation is added to the data packet, the data packet and the messagecell therein are transmitted to a destination represented by thedestination information of the data packet in the packet-orientedcommunication network.
 33. The method according to claim 32, wherein themessage cell transmitted are forwarded according to routing informationcontained in the message cells.
 34. The method according to claim 32,wherein user information contained in the message cell is forwardedaccording to routing information contained in the respective messagecells.
 35. A communication arrangement to at least partially transmitmessage cells to be transmitted in a first communication network via asecond packet-oriented communication network, comprising: prioritiesthat can be assigned respectively to the message cells are provided inthe first communication network, the message cells are transmitted viathe first communication network according to the respective prioritiesassigned; insert tools are provided in the network selected from thegroup consisting of first communication network, second communicationnetwork, and a combination thereof, by means of which tools at least oneof the message cells to be transmitted and comprising the same assignedpriority are added to a user data field of at least one data packet ofthe second packet-oriented communication network; and further assigntools are allocated to the insert tools, by means of which assign toolsa transmission priority derived from the priority of the at least oneadded message cell is assigned to the at least one data packet, whereinthe insert and assign tools are designed in such that the at least onedata packet is at least partially transmitted together with the at leastone added message cell according to the assigned transmission priorityvia the second packet-oriented communication network.
 36. Thecommunication arrangement according to claim 35, wherein the insert andassign tools are designed such that for each priority provided in thefirst communication network respectively the at least one data packetcomprising the correspondingly derived transmission priority is formed,the at least one message cell comprising the corresponding priority isadded to the user data field of the at least one formed data packet, andthe at least one data packet is at least partially transmitted via thesecond communication network.
 37. The communication arrangementaccording to claim 35 wherein the insert tools are designed such thatthe at least one message cell to be transmitted and comprising the sameassigned priority is added to the user data field of the respective atleast one data packet and the at least one data packet is at leastpartially forwarded via the packet-oriented communication networkaccording to the at least one further connection-particular transmissionparameter assigned to the respective at least one message cell added tothe user data field.
 38. A communication device that at least partiallytransmit message cells to be transmitted in a first communicationnetwork via a second packet-oriented communication network arranged inthe communication device, the first communication network assigns apriority to the message cells, the message cells are transmitted via thefirst communication network according to the priority assigned,comprising insert tools are provided in the communication device, bymeans of which tools at least one of the message cells to be transmittedand comprising the same assigned priority are added to a user data fieldof at least one data packet of the second packet-oriented communicationnetwork; and further assign tools assigned to the insert tools arearranged in the communication device, by means of which assign tools atransmission priority derived from the priority of the at least oneadded message cell is assigned to the at least one data packet, whereinthe insert and assign tools are designed in such a way that the at leastone data packet is at least partially transmitted together with the atleast one added message cell according to the assigned transmissionpriority via the second packet-oriented communication network.
 39. Thecommunication device according to claim 38, wherein the insert andassign tools are designed in such a way that for each priority providedin the first communication network respectively the at least one datapacket comprising the correspondingly derived transmission priority isformed, the at least one message cell comprising the correspondingpriority is added to the user data field of the at least one formed datapacket, and at least one data packet is at least partially transmittedvia the second communication network.
 40. The communication deviceaccording to claim 38, wherein the insert and assign tools are arrangedrespectively on at least one connection unit arranged in thecommunication device and connected to the first and second communicationnetwork and/or on at least one central unit centrally arranged in thecommunication device and connected to the first and second communicationnetwork.